Retaining The Uuid; Reading Or Writing The Eca Information - Lenovo ThinkPad T540p Maintenance Manual

2. When the logo is displayed, press Esc. The ThinkPad Config Information Update Utility interface is
displayed.
3. Type 1 under Enter the action desired, then press Enter. The ThinkPad Serial Number Update Utility for
Asset ID screen is displayed.
4. Type 1 under Enter the action desired, then press Enter. Then follow the instructions on the screen
to restore the serial number of the system unit.

Retaining the UUID

The Universally Unique Identifier (UUID) is a 128-bit number uniquely assigned to your computer at
production and stored in the EEPROM of your system board.
The algorithm that generates the number is designed to provide unique IDs until the year A.D. 3400. No two
computers in the world have the same number.
When you replace the system board, perform the following steps to create a new UUID for the system
board if the system board does not have a UUID:
Note: Before you perform the operation, ensure that the UEFI/Legacy setting within the Startup menu in
the ThinkPad Setup program is set to UEFI Only.
1. Connect a USB memory key to the computer.
2. Go to http://www.lenovo.com/maintenanceutilities and follow the instructions on the screen to create a
Maintenance Key.
Note: Only an authorized Lenovo service technician can access the above Web site.
3. Restart the computer.
4. When the logo screen is displayed, press Esc. The ThinkPad Config Information Update Utility interface
is displayed.
5. Type 2 under Enter the action desired, then press Enter. The Auto UUID generation utility interface is
displayed.
6. Type y under Change UUID. OK? [Y/N], then press Enter. A new UUID is created and written. If a
valid UUID already exists, it is not overwritten.

Reading or writing the ECA information

Information on Engineering Change Announcements (ECA) is stored in the EEPROM of the system board.
The electronic storage of this information simplifies the procedure to check if the ECA has been previously
applied to a machine. The machine does not need to be disassembled to check for the ECA application.
To check what ECAs have been previously applied to the machine, use the ECA Information Read/Write
function on the LENOVO ThinkPad Hardware Maintenance Diskette or Maintenance Key.
1. Insert the latest version of LENOVO ThinkPad Hardware Maintenance Diskette or Maintenance Key,
and then restart the computer.
2. From the main menu, select 6. Set ECA Information.
3. To read the ECA information, select 2. Read ECA/rework number from EEPROM and follow the
instructions on the screen; To read box build date, select 5. Read box build date from EEPROM, and
follow the instructions on the screen.
After an ECA has been applied to the machine, the EEPROM must be updated to reflect the ECA's
application. Use the latest version of LENOVO ThinkPad Hardware Maintenance Diskette or Maintenance
Key to update the EEPROM.
Note: Only the ECA number is stored in the EEPROM. The machine type of the ECA is assumed to be the
same as the machine type of the machine that had the ECA applied to it.
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Chapter 8 FRU replacement notices
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